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Chainring Dilemma

Old 03-18-19, 07:50 PM
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Chainring Dilemma

So, I'm working to build a gravel bike using a Niner MTB frame. I have a Shimano SLX 2X (675) crank and want to run it with 44t and 28t chainrings. The SLX is a 110/64 BCD.

The larger ring (44) doesn't have recessed holes in the rear for the bolt nuts to sit flush with the face of the ring. The result is these nuts are impeding the chain on the smaller ring. (Note in the photo that the small ring is reversed, making the gap far too wide.)

Any suggestions?

I can't seem to locate any 44 rings that are recessed in the rear...only the front.

Thanks....

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Old 03-18-19, 08:19 PM
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Use a 44t ring that's made to be a middle one so it's ramps and lift pins are correct WRT the counter bores for the nuts to fit flush. This might require a different crank/bolt pattern. Andy
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Old 03-18-19, 09:01 PM
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Old 03-18-19, 10:19 PM
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I screwed up my own post. The crank is a 104/64 BCD...not 110 as stated in my original posts. Thanks!
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Old 03-19-19, 07:05 AM
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36 is about the biggest 104BCD ring that you can find as a middle.

If You are looking for something on a budget, I would go to the Community Cycling Center on Alberta and see if they have a older road triple crankset. You can take off the ridiculous 54t outer and use the crank as-is and it should be about the gearing that you are looking for.

The other option is a mountain double that you can find in a 28-38, but you will probably only find new.
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Old 03-19-19, 10:03 AM
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SO.. maybe you actually need a 110 - 74 crank, after all, if a 104/64 BCD 44t is only manufactured as an outer chainring..
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Old 03-19-19, 11:12 AM
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Can you add the countersink yourself?
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Old 03-19-19, 11:48 AM
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Originally Posted by ThermionicScott View Post
Can you add the countersink yourself?
Hmmm... tough to find the right tool to do a good flat bottom counterbore.

One might be able to modify one of these to do a 10mm x 12mm counterbore. (verify size).

https://www.snappytools.com/product/...ed-twist-drill

One might be able to do it with a 12mm endmill without a guide, but then it would have to be centered perfectly.
12 0MM Carbide End Mill 4 Flute Metric

Use depth limiter on drill press/mill, or set table to limit depth.
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Old 03-20-19, 04:36 PM
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Ok, looking at that some more:

These are your cranks?



I see the issue with using the outer ring in the middle ring position.

I thought your rings were without a recess, but it is on the wrong side.

I have thought about whether it would be possible to counterbore a recess into the rings, but the remaining material could get mighty thin.

You might be able to grind off part of the bolt heads so they wouldn't interfere, or use a slightly larger small ring.

Looking at rings. You might try a "Flat" ring that should be reversible.

For example the Vuelta Flat rings.

https://www.ebay.com/itm/Vuelta-Mtn-...k/372593545351

Vuelta Flat Mountain Chainring - $12.95 - Bike Parts 360

Unfortunately I'm not seeing photos of both sides.

Or, try a different crankset.
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Old 03-20-19, 08:59 PM
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If you can move to a 110/74 crankset (typical road triple), then Spa Cycles in the UK will have several choices of suitable middle chainrings. They have TA, two or three grades of Stronglight, and their own house brand in 110mm and 74mm BCDs. Here's the house brand, CNC'ed Zicral 44T middles in black or silver:

https://www.spacycles.co.uk/m2b0s210...l-Middle-Inner

I think Zicral is 7071-T something, and I suspect the supplier is Stronglight. They can fix you up with TA as well, and they are the best rings, period.
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